feat: support symlinks for deb and rpm. (#185)

* feat: Support symlinks.

* fix: Fix symlink creation for deb.

* fix: Remove magic number in rpm symlink creation.

* test: Add symlink unit tests.

* test: Add symlink acceptance tests.

* doc: Add documentation for symlinks.

* fix: Fix acceptance test name.

* fix: Make symlink headers more consistent.

acceptance/acceptance_test.go

@@ -210,6 +210,21 @@ func TestDebTriggers(t *testing.T) {
 	})
 }
 
+func TestSymlink(t *testing.T) {
+	for _, format := range formats {
+		format := format
+		t.Run(fmt.Sprintf("symlink-%s", format), func(t *testing.T) {
+			t.Parallel()
+			accept(t, acceptParms{
+				Name:       fmt.Sprintf("symlink_%s", format),
+				Conf:       "symlink.yaml",
+				Format:     format,
+				Dockerfile: fmt.Sprintf("%s.symlink.dockerfile", format),
+			})
+		})
+	}
+}
+
 type acceptParms struct {
 	Name       string
 	Conf       string

acceptance/testdata/deb.symlink.dockerfile

@@ -0,0 +1,6 @@
+FROM ubuntu
+ARG package
+COPY ${package} /tmp/foo.deb
+RUN dpkg -i /tmp/foo.deb
+RUN ls -l /path/to/symlink | grep "/path/to/symlink -> /etc/foo/whatever.conf"
+RUN dpkg -r foo

acceptance/testdata/rpm.symlink.dockerfile

@@ -0,0 +1,6 @@
+FROM fedora
+ARG package
+COPY ${package} /tmp/foo.rpm
+RUN rpm -ivh /tmp/foo.rpm
+RUN ls -l /path/to/symlink | grep "/path/to/symlink -> /etc/foo/whatever.conf"
+RUN rpm -e foo

acceptance/testdata/symlink.yaml

@@ -0,0 +1,12 @@
+name: "foo"
+arch: "amd64"
+platform: "linux"
+version: "v1.2.3"
+maintainer: "Foo Bar"
+vendor: "foobar"
+homepage: "https://foobar.org"
+license: "MIT"
+files:
+  ../testdata/whatever.conf: "/etc/foo/whatever.conf"
+symlinks:
+  /path/to/symlink: "/etc/foo/whatever.conf"

cmd/nfpm/main.go

@@ -154,6 +154,8 @@ files:
   ./bar: "/usr/local/bin/bar"
 config_files:
   ./foobar.conf: "/etc/foobar.conf"
+symlinks:
+  /sbin/foo: "/usr/local/bin/foo"
 overrides:
   rpm:
     scripts:

deb/deb.go

@@ -131,6 +131,10 @@ func createDataTarGz(info *nfpm.Info) (dataTarGz, md5sums []byte, instSize int64
 		return nil, nil, 0, err
 	}
 
+	if err := createSymlinksInsideTarGz(info, out, created); err != nil {
+		return nil, nil, 0, err
+	}
+
 	if err := out.Close(); err != nil {
 		return nil, nil, 0, errors.Wrap(err, "closing data.tar.gz")
 	}
@@ -141,6 +145,27 @@ func createDataTarGz(info *nfpm.Info) (dataTarGz, md5sums []byte, instSize int64
 	return buf.Bytes(), md5buf.Bytes(), instSize, nil
 }
 
+func createSymlinksInsideTarGz(info *nfpm.Info, out *tar.Writer, created map[string]bool) error {
+	for src, dst := range info.Symlinks {
+		if err := createTree(out, src, created); err != nil {
+			return err
+		}
+
+		err := newItemInsideTarGz(out, []byte{}, &tar.Header{
+			Name:     src,
+			Linkname: dst,
+			Typeflag: tar.TypeSymlink,
+			ModTime:  time.Now(),
+			Format:   tar.FormatGNU,
+		})
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
 func createFilesInsideTarGz(info *nfpm.Info, out *tar.Writer, created map[string]bool) (bytes.Buffer, int64, error) {
 	var md5buf bytes.Buffer
 	var instSize int64

deb/deb_test.go

@@ -591,6 +591,39 @@ func TestSymlinkInFiles(t *testing.T) {
 	assert.Equal(t, string(realSymlinkTarget), string(packagedSymlinkTarget))
 }
 
+func TestSymlink(t *testing.T) {
+	var (
+		configFilePath = "/usr/share/doc/fake/fake.txt"
+		symlink        = "/path/to/symlink"
+		symlinkTarget  = configFilePath
+	)
+
+	info := &nfpm.Info{
+		Name:        "symlink-in-files",
+		Arch:        "amd64",
+		Description: "This package's config references a file via symlink.",
+		Version:     "1.0.0",
+		Overridables: nfpm.Overridables{
+			Files: map[string]string{
+				"../testdata/whatever.conf": configFilePath,
+			},
+			Symlinks: map[string]string{
+				symlink: symlinkTarget,
+			},
+		},
+	}
+
+	dataTarGz, _, _, err := createDataTarGz(info)
+	assert.NoError(t, err)
+
+	packagedSymlinkHeader, err := extractFileHeaderFromTarGz(dataTarGz, symlink)
+	assert.NoError(t, err)
+
+	assert.Equal(t, symlink, packagedSymlinkHeader.Name)
+	assert.Equal(t, uint8(tar.TypeSymlink), packagedSymlinkHeader.Typeflag)
+	assert.Equal(t, symlinkTarget, packagedSymlinkHeader.Linkname)
+}
+
 func extractFileFromTarGz(tarGzFile []byte, filename string) ([]byte, error) {
 	tarFile, err := gzipInflate(tarGzFile)
 	if err != nil {
@@ -622,6 +655,32 @@ func extractFileFromTarGz(tarGzFile []byte, filename string) ([]byte, error) {
 	return nil, os.ErrNotExist
 }
 
+func extractFileHeaderFromTarGz(tarGzFile []byte, filename string) (*tar.Header, error) {
+	tarFile, err := gzipInflate(tarGzFile)
+	if err != nil {
+		return nil, err
+	}
+
+	tr := tar.NewReader(bytes.NewReader(tarFile))
+	for {
+		hdr, err := tr.Next()
+		if err == io.EOF {
+			break // End of archive
+		}
+		if err != nil {
+			return nil, err
+		}
+
+		if path.Join("/", hdr.Name) != path.Join("/", filename) {
+			continue
+		}
+
+		return hdr, nil
+	}
+
+	return nil, os.ErrNotExist
+}
+
 func gzipInflate(data []byte) ([]byte, error) {
 	gzr, err := gzip.NewReader(bytes.NewReader(data))
 	if err != nil {

nfpm.go

@@ -153,6 +153,7 @@ type Overridables struct {
 	Conflicts    []string          `yaml:"conflicts,omitempty"`
 	Files        map[string]string `yaml:"files,omitempty"`
 	ConfigFiles  map[string]string `yaml:"config_files,omitempty"`
+	Symlinks     map[string]string `yaml:"symlinks,omitempty"`
 	EmptyFolders []string          `yaml:"empty_folders,omitempty"`
 	Scripts      Scripts           `yaml:"scripts,omitempty"`
 	RPM          RPM               `yaml:"rpm,omitempty"`

rpm/rpm.go

@@ -14,6 +14,7 @@ import (
 
 	"github.com/google/rpmpack"
 	"github.com/pkg/errors"
+	"github.com/sassoftware/go-rpmutils/cpio"
 
 	"github.com/goreleaser/chglog"
 
@@ -103,6 +104,8 @@ func (*RPM) Package(info *nfpm.Info, w io.Writer) error {
 		return err
 	}
 
+	addSymlinksInsideRPM(info, rpm)
+
 	if err = addScriptFiles(info, rpm); err != nil {
 		return err
 	}
@@ -315,6 +318,19 @@ func createFilesInsideRPM(info *nfpm.Info, rpm *rpmpack.RPM) error {
 	return nil
 }
 
+func addSymlinksInsideRPM(info *nfpm.Info, rpm *rpmpack.RPM) {
+	for src, dst := range info.Symlinks {
+		rpm.AddFile(rpmpack.RPMFile{
+			Name:  src,
+			Body:  []byte(dst),
+			Mode:  uint(cpio.S_ISLNK),
+			MTime: uint32(time.Now().UTC().Unix()),
+			Owner: "root",
+			Group: "root",
+		})
+	}
+}
+
 func copyToRPM(rpm *rpmpack.RPM, src, dst string, config bool) error {
 	file, err := os.OpenFile(src, os.O_RDONLY, 0600) //nolint:gosec
 	if err != nil {

rpm/rpm_test.go

@@ -13,6 +13,7 @@ import (
 	"time"
 
 	"github.com/sassoftware/go-rpmutils"
+	"github.com/sassoftware/go-rpmutils/cpio"
 	"github.com/stretchr/testify/assert"
 
 	"github.com/goreleaser/chglog"
@@ -435,6 +436,43 @@ func TestSymlinkInFiles(t *testing.T) {
 	assert.Equal(t, string(realSymlinkTarget), string(packagedSymlinkTarget))
 }
 
+func TestSymlink(t *testing.T) {
+	var (
+		configFilePath = "/usr/share/doc/fake/fake.txt"
+		symlink        = "/path/to/symlink"
+		symlinkTarget  = configFilePath
+	)
+
+	info := &nfpm.Info{
+		Name:        "symlink-in-files",
+		Arch:        "amd64",
+		Description: "This package's config references a file via symlink.",
+		Version:     "1.0.0",
+		Overridables: nfpm.Overridables{
+			Files: map[string]string{
+				"../testdata/whatever.conf": configFilePath,
+			},
+			Symlinks: map[string]string{
+				symlink: symlinkTarget,
+			},
+		},
+	}
+
+	var rpmFileBuffer bytes.Buffer
+	err := Default.Package(info, &rpmFileBuffer)
+	assert.NoError(t, err)
+
+	packagedSymlinkHeader, err := extractFileHeaderFromRpm(rpmFileBuffer.Bytes(), symlink)
+	assert.NoError(t, err)
+
+	packagedSymlink, err := extractFileFromRpm(rpmFileBuffer.Bytes(), symlink)
+	assert.NoError(t, err)
+
+	assert.Equal(t, symlink, packagedSymlinkHeader.Filename())
+	assert.Equal(t, cpio.S_ISLNK, packagedSymlinkHeader.Mode())
+	assert.Equal(t, symlinkTarget, string(packagedSymlink))
+}
+
 func extractFileFromRpm(rpm []byte, filename string) ([]byte, error) {
 	rpmFile, err := rpmutils.ReadRpm(bytes.NewReader(rpm))
 	if err != nil {
@@ -470,6 +508,36 @@ func extractFileFromRpm(rpm []byte, filename string) ([]byte, error) {
 	return nil, os.ErrNotExist
 }
 
+func extractFileHeaderFromRpm(rpm []byte, filename string) (*cpio.Cpio_newc_header, error) {
+	rpmFile, err := rpmutils.ReadRpm(bytes.NewReader(rpm))
+	if err != nil {
+		return nil, err
+	}
+
+	pr, err := rpmFile.PayloadReader()
+	if err != nil {
+		return nil, err
+	}
+
+	for {
+		hdr, err := pr.Next()
+		if err == io.EOF {
+			break // End of archive
+		}
+		if err != nil {
+			return nil, err
+		}
+
+		if hdr.Filename() != filename {
+			continue
+		}
+
+		return hdr, nil
+	}
+
+	return nil, os.ErrNotExist
+}
+
 func symlinkTo(tb testing.TB, fileName string) string {
 	target, err := filepath.Abs(fileName)
 	assert.NoError(tb, err)

www/docs/configuration.md

@@ -97,6 +97,10 @@ config_files:
 empty_folders:
 - /var/log/foo
 
+# Symlinks mapping from symlink name inside package to target inside package (overridable)
+symlinks:
+  /sbin/foo: /usr/local/bin/foo
+
 # Scripts to run at specific stages. (overridable)
 scripts:
   preinstall: ./scripts/preinstall.sh